About one in ten Australian patients with lumbar radiographs has a lumbosacral transitional vertebra. In a minority of them the transitional segment causes persistent low back, buttock or hip pain that is treated for years as non-specific strain. The diagnosis rests on a local anaesthetic block at the transitional articulation, compared against blocks at the facet, sacroiliac joint, L5 root and hip. In a tertiary spine centre, injection at the pseudoarticulation gave greater relief than any other injection, and only the patients whose anatomy had been identified received one.

This guide sets out what a pain physician or interventional radiologist needs: the targets and the comparison sequence, the agents, volumes and criteria the published reports used, the limits of the block, imaging guidance and SPECT-CT, the evidence on therapeutic injection, epidural and transforaminal injection, the radiofrequency reports and the choice of technique, the point at which intervention ends and surgical referral begins, the Medicare items that come closest, and the pitfalls. Two further chapters set out what patients report about their injections and what each referrer needs from the procedure record, and an appendix gives a procedure record template.

Every clinical figure is drawn from the published evidence, and the notes at the end say what could and could not be verified.